1. Field of the Invention
The present invention relates to a developer container of the type including a soft bag whose volume decreases with a decrease in pressure inside the bag, and an outlet forming member forming an outlet for discharging a developer stored in the bag. Also, the present invention relates to a developer conveying device for conveying the developer from the developer container to a developing replenishing device by use of a compressed gas, and an image forming apparatus including the same.
2. Description of the Background Art
An electrophotographic image forming apparatus of the type developing a latent image formed on a photoconductive drum or similar image carrier and transferring the resulting toner image to a sheet is conventional. It is a common practice with this type of image forming apparatus to use a toner container for replenishing fresh toner to a developing unit. Generally, the toner container is delivered to a user as a product independent of the image forming apparatus. This type of image forming apparatus often uses a screw, auger or similar mechanical means for replenishing toner from the toner container to a developing unit little by little. The problem with this kind of toner replenishing system is that a toner conveyance path must be substantially linearly arranged, obstructing free layout.
In light of the above, Japanese Patent Laid-Open Publication No. 7-219329 discloses a toner replenishing system including a screw pump and an air pump. The screw pump includes a rotor rotatable to convey toner in the axial direction and a stator enclosing the rotor while forming a passage between it and the rotor. The air pump sends compressed air to toner being conveyed by the screw pump in order to fluidize the toner. This kind of toner replenishing system promotes free layout of the toner conveyance path because compressed air can convey the toner from a toner container to a developing unit via a flexible tube. The toner container can therefore be provided with any desired shape and size matching with an idle space available in the image forming apparatus. Further, the toner is conveyed together with air and can therefore be stably fluidized and conveyed. In addition, no unnecessary stresses act on the toner during conveyance, so that the toner coheres or sticks little.
Moreover, the toner replenishing system taught in the above document makes it possible to implement the toner container as a flexible bag whose volume decreases with a decrease in pressure inside the bag, which occurs due to the suction of the screw pump. The flexible bag therefore collapses in a compact configuration when run out of toner and is therefore easy to handle. By contrast, a toner cartridge or a hard bottle, which is another specific form of the toner container, does not deform and therefore remains in the same size even when run out of toner. The toner replenishing system taught in the above document allows a soft bottle formed of a soft material to be used. The soft bottle whose volume decreases when run out of toner is easy for the user to handle. In addition, a minimum of cost is necessary for the soft bottle to be transported from the user""s station to the manufacturer""s station.
However, the soft bottle does not collapse in a regular shape, but collapses in an irregular shape as if it were twisted. This impairs the merit of the collapsible toner container as to storage and transport. Moreover, the soft bottle collapsed in an irregular shape is not attractive in appearance or easy to handle.
The toner replenishing system proposed in the above document can convey the toner out of the toner container only with the suction of the screw pump. However, a problem is that the toner deposited on the inner periphery of the toner container does not reach the outlet of the toner container despite the suction, but remains in the toner container in the form of blocks (toner blocking), depending on the shape of the container. To cope with toner blocking, air under pressure may be sent from an air pump into the toner container in parallel with the suction of the screw pump for thereby agitating the toner and removing the toner from the inner periphery of the container. However, while the toner around the outlet of the toner container, in particular, must be surely fluidized, even the combined suction and air scheme fails to surely fluidize it, depending on the shape of the toner container and the air sending system.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 10-97130, 2000-194182, 2000-267412, 2000-267414, and 2000-356898.
It is an object of the present invention to provide a developer container easy to handle, store and transport when run out of a developer, and an image forming apparatus using the same.
It is another object of the present invention to provide a developer conveying device capable of agitating and sufficiently fluidizing toner stored in a toner container by sending compressed air or similar gas into the toner container, and an image forming apparatus using the same.
In accordance with the present invention, a developer container includes a flexible bag whose volume decreases in accordance with the decrease in pressure inside the bag. An outlet forming member forms an outlet for discharging a developer stored in the bag. When the volume of the bag decrease due to the drop of the pressure, a deformation assisting member helps the bag deform to a preselected shape.
Also, in accordance with the present invention, a developer conveying device includes a gas sending device for sending a gas under pressure. An air supply passage guides the gas delivered from the gas sending device to a developer container, which stores a developer therein, via a plurality of gas outlets. A developer passage is formed with a developer inlet for discharging the developer from the developer container. A controller controls the individual flows of the gas into the developer container via the plurality of gas inlets.
An image forming apparatus using the above developer container and including the above developer conveying device is also disclosed.